Question

An aeroplane flying horizontally 1 km above the ground and going away from the observer is observed at an elevation of ${60}^{\circ }$. After 10 seconds, its elevation is boserved to be ${30}^{\circ }$; find the uniform speed of the aeroplane in km per hour.

Answer 1

Tan60°= =√3
⇒d = km
now, the aeroplane cover (d+x) km
tan30°= =
⇒(d+x) = √3
⇒x = √3 -() = 1.15 km
so speed ==
=414 km/hr